Fault processing method, system and exchanging device based on industry ethernet network

ABSTRACT

A fault processing method based on industry Ethernet network, wherein exchanging devices in the network are connected by mutual redundant double links, wherein work link is in working state, the spare link is in spare state, and the method includes: detecting connection states of the double links between the exchanging devices in the network ( 201 ); switching the spare link to the work link when the work link is in fault state and the spare state is in connecting state ( 202 ). A fault processing system and exchanging device based on industry Ethernet network are further provided, which applies the ring structure of mutual redundant double links according to the invention, the network availability is ensured by switching to the spare link when multipoint faults appear in the network; and the time of fault recovery processing is reduced by switching between mutual redundant links.

The present application claims the benefit of Chinese Patent ApplicationNo. 200710167374.2 filed with the Chinese Intellectual Property Officeon Nov. 26, 2007, entitled “Fault Processing Method, System andExchanging Device based on Industry Ethernet Network”, which isincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a technical field of industry Ethernetnetwork, particularly to a fault processing method, system and anexchanging device based on industry Ethernet network.

BACKGROUND OF THE INVENTION

With the development of Ethernet network technology, the Ethernetnetwork has been increasingly applied to industrial fields, andoperation stability and benefit increase of industrial productionrequire more on the availability of the industry Ethernet network incase of fault. In view of the requirement of high availability of theindustry Ethernet network, the existing industry Ethernet networkgenerally uses the master-slave ring network redundancy implementationmechanism which controls the operation of the whole network by a masterexchanging device in the Ethernet network system to ensure that thewhole network is available in the event that a fault occurs in a certainexchanging device in the Ethernet network. However, in the abovemaster-slave ring redundancy implementation mechanism, the fault risk inthe network are highly converged on the master exchanging device, suchthat the whole Ethernet network may be unavailable in the case that afault occurs in the master exchanging device.

In the prior art, in order to overcome the problem that the network willbe unavailable in the event that a fault occurs in the master exchangingdevice in the master-slave ring network redundancy implementationmechanism, a distributed Ethernet network system is used, which includesa plurality of exchanges connected in sequence to form a ring structure.FIG. 1 illustrates a flow chart of implementing a fault processing bythe system:

Step 101: performing configuration for all exchanges in the system.

Step 102: performing periodically loop detection and protocol machinedetection for the system according to an instruction of predeterminedconfiguration.

Step 103: sending a fault alarming message when detecting a loop faultor protocol machine fault.

It can be understood from the existing Ethernet network fault processingmethod that the method implements a distributed fault detection anddiagnosis, indicates the principle of fairness in communication in theEthernet network and solves the problem of highly converged risks ofavailability of Ethernet network resulted from a fault occurred in themaster exchange device. However, in the case that a plurality of faultsoccur in a plurality of exchanging devices in the network, the Ethernetnetwork system will be unavailable since the distributed single ringredundancy network can only process a fault occurred in a singleexchanging device; and when a single fault occurs in the network, sincea message transfer path in exchanging devices has been changed, the timeof fault recovery of the Ethernet network is prolonged, and theavailability of the Ethernet network is correspondingly decreasedbecause an inherent FDB table in exchanging devices need to bereconstructed during fault recovery.

SUMMARY OF THE INVENTION

An object of the invention is to provide a fault processing method basedon industry Ethernet network to solve the problem that the Ethernetnetwork system will be unavailable when a plurality of faults occur in aplurality of exchanging devices in the prior art.

Another object of the invention is to provide a fault processing systemand exchanging device based on industry Ethernet network to solve theproblem that the system will be unavailable when a plurality of faultsoccur in a plurality of exchanging devices in the Ethernet networksystem in the prior art.

In order to solve the above technical problems, the invention providesthe following technical solutions:

A fault processing method based on industry Ethernet network, whereinexchanging devices in the network are connected by mutual redundantdouble links, and wherein the work link is in working state, and thespare link is in spare state, the method comprising:

detecting connection states of the double links between the exchangingdevices in the network; and

switching the spare link to the work link when the work link is in faultstate and the spare state is in connection state.

The connection state of the link include: the link in connection state,the link in fault state or the link in disconnection state.

The exchanging device includes at least four ports, and connects to anadjacent exchanging device thereof via two ports respectively; and twoports of the exchanging device in the same link are ports in the samering, and two ports of the exchanging device connected to the sameexchanging device are ports in the same direction.

Exchanging the spare link to the work link comprises the followingsteps:

searching, by the exchanging device, a port in the same direction withthe fault port which makes the work link in fault state; and

converting the state of the working port in the work link into forbiddenstate, and converting the state of the spare port in the spare link intothe original state of the working port, when the spare link comprisingthe port in the same direction is in connection state.

The converting of the state of the spare port in the spare link into theoriginal state of the working port includes:

the original state of the working port is forwarding state, and thestate of the spare port is converted into forwarding state; or

-   -   the original state of the working port is blocking state, and        the state of the spare port is converted into blocking state.

The method further comprises:

maintaining, by the exchanging device, the state of the spare port inthe spare link and converting the state of the fault port into blockingstate, when fault occurs to both of the double links, or when the worklink is in fault state and the spare link is in disconnection state; and

-   -   informing the working port in blocking state in the network of        conversion into forwarding state.

The method further comprises:

setting the state of the port in the double links according topredetermined configuration and performing clock synchronization whenthe exchanging device in the network is initialized.

The method further comprises:

sending, by the exchanging device, alarm information in a multicastmanner when a fault occurs in the work link, wherein the alarminginformation includes information of fault type and position of the faultoccurred.

A fault processing system based on industry Ethernet network, comprises:a plurality of exchanging devices connected by mutual redundant doublelinks, wherein the work link is in working state, and the spare link isin spare state, wherein the exchanging device comprises:

a detection unit adapted to detect connection state of the double linksbetween adjacent exchanging devices;

an exchanging unit adapted to switch the spare link to the work linkwhen the work link is in fault state and the spare link is in connectionstate.

The switching unit comprises:

a searching unit adapted to search a port in the same direction with thefault port which makes the work link in fault state;

an operation unit adapted to convert the state of the working port inthe work link into forbidden state and convert the state of the spareport in the spare link into original state of the working port, when thespare link comprising the port in the same direction is in connectionstate.

The exchanging device further comprises:

a converting unit adapted to maintain the state of the spare port in thespare link and convert the state of the fault port into blocking statewhen a fault occurs to both of the double links, or the work link is infault state and the spare link is in disconnection state;

an informing unit adapted to inform the working port in blocking statein the network of conversion into a forwarding state.

The exchanging device further comprises:

a setting unit adapted to set the state of the port in the double linksaccording to predetermined configuration and perform clocksynchronization when the exchanging device in the network isinitialized;

an alarming unit adapted to send alarming information in a multicastmanner when a fault occurs in the work link, wherein the alarminformation includes information of fault type and position of the faultoccurred.

An exchanging device comprises:

a detection unit adapted to detect a connection state of the doublelinks between the exchanging devices connected thereto;

a switching unit adapted to switch the spare link to the work link whenthe work link is in fault state and the spare link is in connectionstate.

The switching unit comprises:

a searching unit adapted to search a port in the same direction with thefault port which makes the work link in fault state;

an operation unit adapted to convert the state of the working port inthe work link into a forbidden state and convert the state of the spareport in the spare link into the original state of the working port, whenthe spare link comprising the port in the same direction is inconnection state.

The exchanging device further comprises:

a converting unit adapted to maintain the state of the spare port in thespare link and convert the state of the fault port into blocking state,when a fault occurs to both of the double links, or when the work linkis in fault state and the spare link is in disconnection state;

an informing unit adapted to inform the working port in blocking statein the network of conversion into forwarding state.

The exchanging device further comprises:

a setting unit adapted to set the state of the ports in the double linksaccording to predetermined configuration and perform clocksynchronization when the exchanging device in the network isinitialized;

an alarming unit adapted to send alarm information in a multicast mannerwhen a fault occurs on the work link, wherein the alarm informationincludes information of fault type and position of the fault occurred.

It can be understood from the solutions provided in the invention, theexchanging devices in the network of the invention are connected bymutual redundant double links, wherein the work link is in workingstate; the spare link is in spare state; the connection state of thedouble links in the exchanging devices of the network is detected; thespare link is switched to the work link when the work link is in faultstate and the spare state is in connection state. When a plurality offaults occur in the ring structure of mutual redundant double links inthe invention, the network availability is ensured by switching to thespare link; and a re-direction time required by transmitting the normaldata resulted from a change of the data transfer path during redundancyswitching in a single ring network structure is avoided by switching inmutual redundant links, such that the time of fault recovery in thenetwork is shortened.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a flow chart of a fault processing method in the prior art;

FIG. 2 is a flow chart of a fault processing method based on industryEthernet network according to a first embodiment of the invention;

FIG. 3 is a schematic view of the state of the ports connected as doublelinks between exchanging devices;

FIG. 4 is a schematic view of the connection of the ports between twoexchanging devices according to the invention;

FIG. 5 is a flow chart of a fault processing method based on industryEthernet network according to a second embodiment of the invention;

FIG. 6 is a flow chart of a fault processing method based on industryEthernet network according to a third embodiment of the invention;

FIG. 7 is a flow chart of a fault processing method based on industryEthernet network according to a fourth embodiment of the invention;

FIG. 8 is a schematic view of a structure of the fault processing systembased on the industry Ethernet network according to the invention;

FIG. 9 is a block diagram of a exchanging device according to a firstembodiment of the invention; and

FIG. 10 is a block diagram of an exchanging device according to a secondembodiment of the invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The core of the invention is to provide a fault processing method basedon industry Ethernet network, and exchanging devices in the network areconnected by mutual redundant double links, wherein the work link is inworking state; the spare link is in spare state; the connection state ofthe double links between the exchanging devices in the network isdetected; and the spare link is switched to the work link when the worklink is in fault state and the spare state is in connection state.

In order to make those skilled in the art understand the technicalsolution of the invention, and make the objects, features and advantagesof the invention obvious, the invention will be described in detailhereinafter with reference to the appended drawings and the embodiments.

FIG. 2 illustrates a flow chart of a fault processing method based onindustry Ethernet network according to a first embodiment of theinvention. The exchanging devices in the industry Ethernet network areconnected by mutual redundant double links, wherein the work link is inworking state and the spare link is in spare state:

Step 201: detecting connection states of the double links betweenexchanging devices in the network.

Wherein the connection states of the link include the following: thelink is in connection state, the link is in fault state or the link isin disconnection state. The port of the link in connection state definesthat the connection of the link is normal based on the IEEE802.3protocol, and a data exchanging can be normally implemented betweenadjacent exchanging devices via the port; the port of the link indisconnection state defines that the connection of link is in faultbased on IEEE802.3 protocol, and no data exchanging can be performed viathe port; and the port of the link in fault state defines that theconnection of the link is normal based on IEEE802.3 protocol, but nodata exchanging can be implemented between adjacent exchanging devicesvia the port since a fault occurred in the adjacent exchanging device.

Wherein each of the exchanging devices in the network includes at leastfour ports, and connects to the adjacent exchanging devices thereof viatwo ports respectively; two ports of the exchanging device in the samelink are ports in the same ring, and two ports of the exchanging deviceconnected to the same, exchanging device are ports in the samedirection.

Step 202: exchanging the spare link to the work state when the work linkis in fault state and the spare link is in connection state.

Specifically, the exchanging device searches a port in the samedirection with the fault port which makes the work state in fault state;and converts the state of the working port in the work link into aforbidden state and converts the state of the spare port in the sparelink into the original state of the working port when the spare linkcomprising the port in the same direction is in connection state. In thecase that the original state of the working port is forwarding state,the state of the spare port is converted into forwarding state; and inthe case that the original state of the working port is blocking state,the state of the spare port is converted as a blocking state.

FIG. 3 illustrates a schematic view of the state of the port connectedas double links structure between exchanging devices in the Ethernetnetwork according to the invention:

FIG. 3 illustrates an exchanging device A, an exchanging device B, anexchanging device C, an exchanging device D, an exchanging device E andan exchanging device F mutually connected as a ring structure by doublelinks. Ports in the same ring of all devices on an internal ring linkare in forbidden state; ports in the same ring of the five exchangingdevices except the exchanging device D on an external links are inforwarding state. Regarding two ports of the exchanging device D on theexternal ring, one is set in forwarding state, and the other is set inblocking state. Therefore, a loop will not be formed in the network inthis setting manner to prevent a networking storm efficiently; and allports in forbidden state in a corresponding internal ring link are spareports, such that the internal ring link is the spare link of theexternal ring link acting as the work link.

In a double link structure of the Ethernet network according to theinvention, during initializing the exchanging device, all ports in onering are set in forbidden state, and one of all of the ports in theother ring is set in blocking state and the others are set in forwardingstate according to the predetermined configuration. Duringinitialization, the ports of the exchanging device perform clocksynchronization and configuration functions of devices; the ports of theexchanging devices in forwarding state forward all the data messagepassing through the ports; the port of the exchanging devices inblocking state only sends connection detection request message and linkdetection response message between exchanging devices, and discards anyother data messages; and the ports of the exchanging devices inforbidden state discard all data messages.

FIG. 4 illustrates a schematic view of the connection of the portsbetween exchanging devices according to the invention, which is taken inconjunction with the schematic view of the state of the ports connectedas double links between exchanging devices:

The two exchanging devices are interconnected by two pairs of mutuallyredundant ports, wherein one pair of the ports interconnected areworking ports, and the other pair of the ports interconnected are spareports. When no fault occurs in the links between the two exchangingdevices, the state of the working port in the ports in the samedirection on each of the exchanging devices is in forwarding state orblocking state, and the spare port in the ports in the same direction isin forbidden state. The port in forwarding state will forward all of thedata on the ports; the port in blocking state only sends a connectiondetection request message and a connection detection response messagebetween the two exchanging devices, and discards any other datamessages; and the ports in forbidden state does not forward any data.When the port in forwarding state detects a connection fault, theexchanging device can switch the working port to keep normal datacommunication when occurring a fault in the work link of the exchangingdevice.

FIG. 5 illustrates a flow chart of a fault processing method based onindustry Ethernet network according to a second embodiment of theinvention, which is taken in conjunction with the schematic view of adouble link structure of the exchanging device shown in FIG. 3. Theembodiment illustrates a flow chart of a fault processing when a faultonly occurs in the work link, and the spare link is in connection statein the network:

Step 501: detecting connection state of double links between networkdevices.

The exchanging device in the industry Ethernet network according to theinvention performs redundant connection with adjacent exchanging deviceby an independent pair of ports in the same direction, wherein one portis a working port, the other port is a spare port, and all theexchanging devices are connected in sequence to form a double linkstructure in ring.

In this embodiment, when a fault occurs in the work link, the port inthe link defines that the connection of the link is normal based onIEEE802.3 protocol, but data can not be exchanged with an adjacentexchanging device via this port since a fault occurred in the adjacentdevice; and the spare link is in connection state, and the port in thelink defined that the connection of the link is normal based onIEEE802.3 protocol, and data can be exchanged with the adjacentexchanging device via this port normally.

Step 502: determining whether the work link is in fault state, if so,executing Step 503; otherwise, executing Step 505.

Step 503: searching, by the exchanging device, a port in the samedirection with the fault port which makes the work link in the faultstate.

Step 504: converting the state of the working port in the work link intoforbidden state, converting the state of the spare port in the sparelink into original state of the working port; and terminating thecurrent procedure.

When the original state of the working port is forwarding state, thestate of the spare port is converted into forwarding state; and when theoriginal state of the working port is blocking state, the state of thespare port is converted into blocking state.

Step 505: maintaining the work state of the work link and the statesetting of the ports in the work link; and terminating the currentprocedure.

FIG. 6 illustrates a flow chart of a fault processing method based onindustry Ethernet network according to a third embodiment of the of theinvention, which is taken in conjunction with the schematic view of thedouble link structure of the exchanging device shown in FIG. 3. Theembodiment illustrates a flow chart of a fault processing based on thestate of the spare link when a fault occurs to the work link in thenetwork.

Step 601: detecting connection state of double links between networkdevices.

When the spare link is in connection state, the connection of the linkis normal, and data can be exchanged with the adjacent exchanging devicevia this port normally; when the spare link is in disconnection state,the connection of the link is in fault, and data can not be exchangedwith other exchanging device via this port; when the spare link is infault state, the connection of the link is normal, but data can not beexchanged with an adjacent exchanging device via this port since a faultoccurred on the adjacent device.

Step 602: determining the state of the spare link when the work link isin fault, if the state thereof is in connection state, executing Step603; if the state thereof is in disconnection or fault state, executingStep 604.

Step 603: switching the spare link to the work link; and terminating thecurrent procedure.

the exchanging device searches a port in the same direction with thefault port which makes the work state in fault state, and converts thestate of the working port in the work link into forbidden state andconverts the state of the spare port in the spare link into the originalstate of the working port when the spare link comprising the port in thesame direction is in connection state. That is, when the original stateof the working port is forwarding state, the state of the spare port isconverted into forwarding state; and when the original state of theworking port is blocking state, the state of the spare port is convertedinto blocking state.

Step 604: maintaining the state of the spare port in the spare link, andconverting the state of the fault port into blocking state.

When the link connection state of ports in the same direction of theexchanging device are all in disconnection state, the work state of thelink is recovered by the exchanging device in the network through theconnection recovery technique, that is, the exchanging devicecontinuously detects whether the connection state of the port is normal,if it is detected that the connection state of one of the ports in thesame direction of the exchanging device is normal, the exchanging devicedirectly sets the port as forwarding state; otherwise, the detectionwill be continued; and if it is detected that the connection state ofthe other port in the same direction of the exchanging device is alsonormal, the exchanging device sets the port as forbidden state.

Step 605: informing working port in blocking state in the network ofconversion into forwarding state, and terminating the current procedure.

FIG. 7 illustrates a flow chart of a fault processing method based onindustry Ethernet network according to a fourth embodiment of theinvention, which is taken in conjunction with the schematic view of thedouble link structure of the exchanging device shown in FIG. 3. Theembodiments illustrates a detailed flow chart of the fault processingmethod based on industry Ethernet network:

Step 701: setting the state of the ports in double links according tothe predetermined configuration and performing clock synchronizationduring initializing the exchanging device.

Step 702: detecting the connection states of the double links betweenexchanging devices in the network.

Step 703: determining whether a fault occurs in the work link, if thefault occurs, executing Step 704; otherwise, executing Step 710.

Step 704: sending, by the exchanging device, the alarming informationincluding information of fault type and position of the fault occurredin a multicast manner.

Step 705: determining the state of the spare link, if it is inconnection state, executing Step 706; and if it is in fault ordisconnection state, executing Step 708.

Step 706: searching, by the exchanging device, a port in the samedirection with the fault port which makes the work link in fault state.

Step 707: converting the state of the working port in the work link intoforbidden state, converting the state of the spare port in the sparelink into the original state of the working port, and terminating thecurrent procedure.

Step 708: maintaining the state of the spare port in the spare link, andconverting the state of the fault port into blocking state.

Step 709: informing the working port in blocking state in the network ofconversion into forwarding state, and terminating the current procedure.

Step 710: maintaining the work state of the work link and the statesettings of the ports in the work link; and terminating the currentprocedure.

Corresponding to the fault processing method based on industry Ethernetnetwork, the invention further provides a fault processing system basedon industry Ethernet network.

FIG. 8 illustrates a structurally schematic view of the fault processingsystem based on industry Ethernet network according to the invention.For illustrating conveniently, there are four exchanging devicesillustrated in the schematic view, that is, an exchanging device 810, anexchanging device 820, an exchanging device 830 and an exchanging device840. The four exchanging devices are connected by mutual redundantdouble links, the external ring is a work link in working state, and theinternal ring is a spare link in spare state.

Each of the exchanging devices in the system includes a detection unitadapted to detect the connection states of the double links betweenadjacent exchanging devices; a switching unit adapted to switch thespare link to the work link when the work link is in fault state and thespare link is in connection state, wherein the switching unit furtherincludes a searching unit adapted to search a port in the same directionwith the fault port which makes the work link in fault state, anoperation unit adapted to convert the state of the working port in thework link into forbidden state and convert the state of the spare portin the spare link into the original state of the working port when thespare link comprising the port in the same direction is in connectionstate.

Furthermore, the exchanging device may further include a converting unitadapted to maintain state of the spare ports in the link and convert thestate of the fault port into blocking state when a fault occurs to bothof the double links, or the work link is in fault state and the sparelink is in disconnection state; an informing unit adapted to inform theworking port in blocking state in the network of conversion intoforwarding state; a setting unit adapted to set the state of the portsin the double link according to the predetermined configuration andperform clock synchronization during initializing the exchanging devicein the network; and an alarming unit adapted to send the alarminformation in the multicast manner when a fault occurs on the worklink, wherein the alarming information includes information of faulttype and position of the fault occurred.

Corresponding to the fault processing method and system based onindustry Ethernet network, the invention further provides an exchangingdevice.

FIG. 9 illustrates a block diagram of an exchanging device according toa first embodiment of the invention.

The exchanging device includes a detection unit 910 and a switching unit920.

The detection unit 910 is adapted to detect the connection states of thedouble links between the exchanging device connected thereto; and theswitching unit 920 is adapted to switch the spare link to the work linkwhen the work link is in fault state and the spare link is in connectionstate.

FIG. 10 illustrates an exchanging device according to a secondembodiment of the invention.

The exchanging device includes: a setting unit 1010, a detecting unit1020, a switching unit 1030, a converting unit 1040, an informing unit1050 and an alarming unit 1060.

The setting unit 1010 is adapted to set the state of the ports in thedouble link according to the predetermined configuration and performclock synchronization during initializing the exchanging device in thenetwork; the detection unit 1020 is adapted to detect the connectionstates of the double links between the exchanging device connectedthereto; and the switching unit 1020 is adapted to switch the spare linkto the work link when the work link is in fault state and the spare linkis in connection state; the converting unit 1040 is adapted to maintainstate of the spare ports in the link and convert the state of the faultport into blocking state when a fault occurs on both of the doublelinks, or when the work link is in fault state and the spare link is indisconnection state; an informing unit 1050 is adapted to inform theworking port in blocking state in the network of conversion intoforwarding state; and an alarming unit 1060 is adapted to send the alarminformation in the multicast manner when a fault occurs on the worklink, wherein the alarming information includes information of faulttype and position of the fault occurred.

Wherein, the switching unit 1030 includes a searching unit 1031 adaptedto search a port in the same direction with the fault port which makesthe work link in fault state; and an operation unit 1032 adapted toconvert the state of the working port in the work link into forbiddenstate and convert the state of the spare port in the spare link intooriginal state of the working port when the spare link comprising theport in the same direction is in connection state.

As can be understood from the embodiments of the invention, the ringstructure of mutual redundant double links according to the inventioncan ensure the network availability by switching to the spare link whenmultipoint faults appear in the network; and a re-direction timerequired by transmitting the normal data resulted from a change of thedata transfer path during redundancy switching in a single ring networkstructure is avoided by switching in mutual redundant links, such thatthe time of fault recovery in the network is shortened.

Although the invention is described through embodiments, thoseordinarily skilled in the art should appreciate that the invention hasmodifications and variations without departing from the spirit of theinvention, and the appended claims are intended to include thosemodifications and variations without departing from the spirit of theinvention.

1. A fault processing method based on industry Ethernet network,characterized in that exchanging devices in the network are connected bymutual redundant double links, wherein work link is in working state,spare link is in spare state, the method comprising: detectingconnection states of the double links between the exchanging devices inthe network; and switching the spare link to the work link when the worklink is in fault state and the spare state is in connection state. 2.The method according to claim 1, characterized in that the connectionstate of the link includes: the link in connection state, the link infault state or the link in disconnection state; The exchanging deviceincludes at least four ports, and connects to an adjacent exchangingdevice thereof via two ports respectively; two ports of the exchangingdevice in the same link are ports in the same ring, and two ports of theexchanging device connected to the same exchanging device are ports inthe same direction.
 3. The method according to claim 2, characterized inthat the switching the spare link to the work link comprises thefollowing steps: searching, by the exchanging device, a port in the samedirection with the fault port which makes the work link in the faultstate; and converting the state of the working port in the work linkinto forbidden state and converting the state of the spare port in thespare link into an original state of the work link when the spare linkcomprising the port in the same direction is in connection state.
 4. Themethod according to claim 3, characterized in that the converting of thestate of the spare port in the spare link to the original state of theworking port comprises: the original state of the working port isforwarding state, and the state of the spare port is converted intoforwarding state; or the original state of the working port is blockingstate, and the state of the spare port is converted into blocking state.5. The method according to claim 2, characterized by further comprising:maintaining, by the exchanging device, the state of the spare port inthe spare link and converting the state of the fault port into blockingstate when fault occurs to both of the double links or when the worklink is in fault state and the spare link is in disconnection state; andinforming the working port in blocking state in the network ofconversion into forwarding state.
 6. The method according to claim 2,characterized by further comprising: setting the state of the port inthe double links according to predetermined configuration and performingclock synchronization when the exchanging device in the network isinitialized.
 7. The method according to claim 1, characterized byfurther comprising: sending, by the exchanging device, alarm informationin the multicast manner when a fault occurs to the work link, whereinthe alarming information includes information of fault type and positionof the fault occurred.
 8. A fault processing system based on industryEthernet network, characterized by comprising: a plurality of exchangingdevices connected by mutual redundant double links, wherein the worklink is in working state, the spare link is in spare state, and theexchanging device comprising: a detection unit adapted to detectconnection states of the double links between adjacent exchangingdevices; a switching unit adapted to switch the spare link to the worklink when the work link is in fault state and the spare link is inconnection state.
 9. The system according to claim 8, characterized inthat the switching unit comprises: a searching unit adapted to search aport in the same direction with the fault port which makes the work linkin fault state; an operation unit adapted to convert the state of theworking port in the work link into forbidden state and convert the stateof the spare port in the spare link into original state of the workingport when the spare link comprising the port in the same direction is inconnection state.
 10. The system according to claim 8, characterized inthat the exchanging device further comprises: a converting unit adaptedto maintain the state of the spare port in the spare link and convertthe state of the fault port into blocking state when a fault occurs toboth of the double links or when the work link is in fault state and thespare link is in disconnection state; an informing unit adapted toinform the working port in blocking state in the network of conversioninto forwarding state.
 11. The system according to claim 8,characterized in that the exchanging device further comprises: a settingunit adapted to set the state of the ports in the double links accordingto predetermined configuration and perform clock synchronization whenthe exchanging device in the network is initialized; an alarming unitadapted to send alarm information in a multicast manner when a faultoccurs on the work link, wherein the alarm information includesinformation of fault type and position of the fault occurred.
 12. Anexchanging device, characterized by, comprising: a detection unitadapted to detect connection states of the double links betweenexchanging devices interconnected; a switching unit adapted to switchthe spare link to the work link when the work link is in fault state andthe spare link is in connection state.
 13. The exchanging deviceaccording to claim 12, characterized in that the switching unitcomprises: a searching unit adapted to search a port in the samedirection with the fault port which makes the work link in fault state;an operation unit adapted to convert the state of the working port inthe work link into forbidden state and convert the state of the spareport in the spare link into the original state of the working port whenthe spare link comprising the port in the same direction is inconnection state.
 14. The exchanging device according to claim 12,characterized by further comprising: a converting unit adapted tomaintain the state of the spare port in the spare link and convert thestate of the fault port into blocking state when a fault occurs to bothof the double links or when the work link is in fault state and thespare link is in disconnection state; an informing unit adapted toinform the working port in blocking state in the network of conversioninto a forwarding state.
 15. The exchanging device according to claim12, characterized by further comprising: a setting unit adapted to setthe state of the ports in the double links according to predeterminedconfiguration and perform clock synchronization when the exchangingdevice in the network is initialized; an alarming unit adapted to sendalarm information in a multicast manner when a fault occurs on the worklink, wherein the alarm information includes information of fault typeand position of the fault occurred.
 16. The method according to claim 2,characterized by further comprising: sending, by the exchanging device,alarm information in the multicast manner when a fault occurs to thework link, wherein the alarming information includes information offault type and position of the fault occurred.